Battery status detection is critical to the power management of portable devices and outdoor devices. For example, in the state of charge (SOC) of a battery (also known as residual power percentage), a typical battery-side voltage division approach may determine the state of charge of a corresponding battery according to the interval where the terminal voltage of the battery is found. This approach has a relatively simple structure, but the state of charge of the battery may not be precisely displayed, and the error can be somewhat large when the charge or discharge current is relatively large.